W

• Water Break - the ability of the rinse to cover the entire surface in an unbroken film.
• Water Column - A tube filled with water and attached to the front of a transducer to couple an ultrasonic beam to a test object. A delay line between the initial pulse and the front surface signal. Also serves as a coupling device. See also delay line.
• Water Jet - An unsupported stream of water carrying ultrasonic signals between the transducer and the test object surface. Also called a squirter.
• Water Path - In immersion testing or with a water column, the distance from the transducer face to the test object’s front surface.
• Water Soluble - The ability to be dissolved in water.
• Water Suspendible - Particles that will not dissolve in water.
• Water Washable Penetrant - A penetrant containing emulsifying such that it does not require the allocation of a separate emulsifying agent to facilitate removal by eater rinsing.
• Wavefront - In a wave disturbance, the locus of points having the same phase.
• Wave Interference - The production of a series of maxima and minima of sound pressure as a consequence of the superposition of waves having different phases.
• Wave Propagation - The way in which a wave travels through a medium.
• Wave Train - A Series of waves or groups of waves passing along the same course at regular intervals.
• Wavelength - The distance needed in the propagation direction for a wave to go through a complete cycle.
• Weldments - Welded joints.
• Wear - The undesired removal of material from contacting surfaces by mechanical action.
• Wear Face - A protective material on the face of a transducer to prevent wear of the piezoelectric element.
• Wedge - A device used to direct ultrasonic energy into a test object at an acute angle. See also shoe.
• Wedge Testing - the use of a wedge between crystal and surface of test pieces where it is not possible to direct waves in the desired direction using straight contact methods. The wedge directs the wave into the test piece at an angle, enabling the wave to reach surfaces, otherwise inaccessible.
• Weld Bead - a deposit of filler metal from a single welding pass.
• Weld Crack - A crack in weld metal.
• Weld Line - The junction of the weld metal and the base metal, or the junction of the base-metal parts when filler metal is not used.
• Weld Metal - That portion of a weld which has been melted during welding.
• Weld Nugget - The weld metal in spot, seam or projection welding.
• Wet Developer - A developer in which the developing powder is applied as a suspension or solution in a liquid, usually water.
• Wetting Agent - A substance that will reduce the surface tension of a liquid, thereby reducing the formation of air bubbles.
• Wheel Transducer - A device that couples ultrasonic energy to a test object through the rolling contact area of a wheel containing a liquid and one or more transducers.
• Workload - The output of a radiation machine or a radioactive source integrated over a suitable time and expressed in appropriate units.
• Worm Holes - Elongated or tubular cavities due to entrapped gas.
• Wrap Around - the display of misleading ultrasonic reflections from a previously transmitted pulse due to the use of excessive pulse repetition frequency. See ghost.